Wednesday, August 12, 2015

A Good Night with the Mallincam DSm!

I had a good night last night with the DSm. I did not go to the observatory, but set up my ETX125 OTA on my EQ Pro mount in the driveway. I used an Orion .5x focal reducer and Skyglow filter. Thanks to everyone who dropped by my NSN broadcast—your thoughts and comments were helpful and appreciated.

I focused on just one object last night—the Ring Nebula—and gave the camera a “workout” on this object. The final and best images were captured with a gain of 5(!) and a 30-second integration time with dark field processing (just 2 darks captured during the session).  The results were very good—dark field processing really does remove any noise more or less completely. I discovered this when I was taking the darks themselves: the images taken showed some noise, but I accidentally left the scope covered for the first exposure after I enabled dark field correction. When the screen updated, the image went from a noisy field to a deep, velvety dark—impressive indeed. The subsequent images were all taken at high gain to minimize the unguided exposure time. While this would normally produce very grainy images, the dark field correction did a superb job.

Below are 2 images--the first is the "raw" image from the camera and the second has been tweaked (levels only) in Photoshop. Click each for a larger image.

The Ring Nebula image de-interlaced and with boosted levels. Note that the central white dwarf star is clearly visible

The original "raw" image as captured by the DSm